# Equivalent map projection

## What are the 3 different types of map projections?

Types of Map Projections

• Cylindrical. A cylindrical projection is any projection in which the meridians are mapped to parallel spaced vertical lines and latitudes are mapped to horizontal lines.
• Pseudocylindrical. …
• Van der Grinten Projection. …
• Conic Projection. …
• Pseudoconic Projection. …

## What are the different kinds of map projection?

• The gnomonic projection displays great circles as straight lines. …
• The orthographic projection maps each point on the Earth to the closest point on the plane. …
• Near-sided perspective projection, which simulates the view from space at a finite distance and therefore shows less than a full hemisphere, such as used in The Blue Marble 2012 ).

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## What is the most well known map projection?

• Mercator projection for navigational purposes
• Robinson or Winkel Tripel projection for mapping the whole Earth
• Plate Carrée for city maps or other small areas
• Equidistant conic for regional mapping and small countries
• Cylindircal Equal Area for equatorial regions
• Lambert Azimuthal Equal Area for continents and polar regions

## How to define map projections?

To define or change the projection of the dataframe:

• Right-click in the map and select Properties > Coordinate System.
• Select the Coordinate System tab.
• Choose a coordinate system from the tree or click the Import button and browse to a data source that is defined with the coordinate system you want to use.

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## What is an equivalent map projection?

An equal area projection is a map projection that shows regions that are the same size on the Earth the same size on the map but may distort the shape, angle, and/or scale. This Mollewide Projection map correctly shows the areas of features with relation to each other but distorts the shapes of features.

## What is an example of an equivalent projection?

In an equal area projection, Tissot circles are all the same relative size across the map. Despite how the Tissot indicatrix changes from a circle to an ellipse, this projection retains relative size.

## What property does an equivalent map projection preserve?

areal relationshipsEquivalent. Equivalent projections preserve areal relationships. This means that comparisons between sizes of land-masses (e.g., North America vs. Australia) can be properly made on equal area maps.

## What are the 4 types of map projections?

What Are The 4 Main Types Of Map projectionsAzimuthal projection.Conic projection.Cylindrical projection.Conventional projection or Mathematical projection.

## What are equivalent maps used for?

Equivalent projections are widely used for thematic maps showing scenario distribution such as population, farmland distribution, forested areas, etc.

## What are the 3 types of projection?

This group of map projections can be classified into three types: Gnomonic projection, Stereographic projection and Orthographic projection.Gnomonic projection. The Gnomonic projection has its origin of light at the center of the globe. … Stereographic projection. … Orthographic projection.

Advantage: The Equal-Area map projection show the correct sizes of landmasses and continents. Disadvantage: The Equal area map causes the shapes of landmasses to be altered and forced into curves. Who uses it? Researchers use Equal-Area maps to compare land sizes of the world.

## What are the properties of an equivalence projection multiple answers )?

Five essential characteristic properties of map projections are subject to distortion: shape, distance, direction, scale, and area….The technical meanings of these terms are described below.Shape (also called conformality) … Distance (also called equidistance) … Direction. … Scale. … Area (also called equivalence)

## What are the 4 main map projection properties?

These map projection properties are area, shape, distance, and direction. These four map projection properties described for facets of a map projection that can either be held true, or be distorted. Of the four projection properties, area and shape are considered major properties and are mutually exclusive.

## What are the 5 most common map projections?

IntroductionProjectionTypeKey virtuesStereographicazimuthalconformalLambert Conformal ConicconicconformalMercatorcylindricalconformal and true directionRobinsonpseudo-cylindricalall attributes are distorted to create a ‘more pleasant’ appearance1 more row

## Is Mercator equal area projection?

The Mercator projection doesn’t preserve area correctly, especially as you get closer to the poles. On the other hand, one kind of projection that doesn’t distort area is the Cylindrical Equal Area.

## What is the most common map projection?

1. Mercator. This projection was developed by Gerardus Mercator back in 1569 for navigational purposes. Its ability to represent lines of constant course from coast to coast made it the perfect map for sailing the seas.

## What are the two main types of projection?

There are two type of projection parallel and perspective.

## What type of projection is Mercator?

Mercator is a cylindrical projection. The meridians are vertical lines, parallel to each other, and equally spaced, and they extend to infinity when approaching the poles.

## What type of projection does Google maps use?

We accept imagery projected using a standard cartographic projection such as Universal Transverse Mercator (UTM), a satellite-based datum such as GRS80, or WGS84; or in Geographic Coordinates (aka “latitude/longitude”) with WGS84 datum. Images should be north-aligned and have rotation parameters set to zero.

## What are the advantages and disadvantages of an equal area projection?

Advantage: The Equal-Area map projection show the correct sizes of landmasses and continents. Disadvantage: The Equal area map causes the shapes of landmasses to be altered and forced into curves. Who uses it? Researchers use Equal-Area maps to compare land sizes of the world.

## Why do different map projections exist?

Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. The study of map projections is the characterization of the distortions.

## Why is it impossible to construct a map projection that is both equal-area and conformal?

Because the sphere is not a developable surface, it is impossible to construct a map projection that is both equal-area and conformal.

## What is the purpose of a map?

The purpose of the map determines which projection should form the base for the map. Because many purposes exist for maps, a diversity of projections have been created to suit those purposes. Another consideration in the configuration of a projection is its compatibility with data sets to be used on the map.

## What is projection in photography?

Despite the name’s literal meaning, projection is not limited to perspective projections, such as those resulting from casting a shadow on a screen, or the rectilinear image produced by a pinhole camera on a flat film plate. Rather, any mathematical function that transforms coordinates from the curved surface distinctly and smoothly to the plane is a projection. Few projections in practical use are perspective.

## Why are maps projections important?

Map projections can be constructed to preserve some of these properties at the expense of others. Because the curved Earth’s surface is not isometric to a plane, preservation of shapes inevitably leads to a variable scale and, consequently, non-proportional presentation of areas.

## Which projection was the first pseudocylindrical projection?

Sinusoidal, which was the first pseudocylindrical projection developed. On the map, as in reality, the length of each parallel is proportional to the cosine of the latitude. The area of any region is true.

## How many steps are involved in creating a map projection?

The creation of a map projection involves two steps:

## What is map projection?

Map projections. A map projection is used to portray all or part of the round Earth on a flat surface. This cannot be done without some distortion. Every projection has its own set of advantages and disadvantages. There is no “best” projection.

## How many map projections does the USGS use?

After decades of using only one map projection, the Polyconic, for its mapping program, the U.S. Geological Survey (USGS) now uses sixteen of the more comnon map projections for its published maps. For larger scale maps, including topographic quadrangles and the State Base Map Series, conformal projections such as the Transverse Mercator and the…

## What is the scale of a map?

A large-scale (1:24,000) 7.5-minute US GS topographic map based on the Transverse Mercator projection is nearly correct in every respect.

## What is the USGS map?

The best known USGS maps are the 1:24,000-scale topographic maps, also known as 7.5-minute quadrangles. Download all dates and scales of USGS topographic maps free of charge from the following applications or order paper copies of all…

## What is UTM zone?

UTM zones are numbered consecutively beginning with Zone 1, which includes the westernmost point of Alaska, and progress eastward to Zone 19, which includes Maine. If UTM ticks are shown on a USGS… A map projection is used to portray all or part of the round Earth on a flat surface.

## How many zones are there in the US?

The Universal Transverse Mercator grid that covers the conterminous 48 United States comprises 10 zones—from Zone 10 on the west coast through Zone 19 in New England. In each zone,coordinates are measured north and east in meters.

## What are the three arrows on a map?

A diagram at the bottom of most USGS topographic maps shows three north arrows–true north, grid north, and magnetic north–and the angles between them. Some maps, especially very old maps, do not have this diagram. Example of north arrows from US…

## What is projection on a map?

The term “projection” implies that the ball-shaped net of parallels and meridians is transformed by casting its shadow upon some flat, or flattenable, surface. While almost all map projection methods are created using mathematical equations, the analogy of an optical projection onto a flattenable surface is useful as a means to classify the bewildering variety of projection equations devised over the past two thousand years or more.

## What are some examples of map projections?

The example shown above is the Polyconic projection, where parallels are all non-concentric circular arcs, except for a straight equator, and the centers of these circles lie along a central axis. The U.S. Geological Survey used the polyconic projection for many years as the basis of its topographic quadrangle map series until the conformal Transverse Mercator succeeded it. Another example is the Robinson projection, which is often used for small-scale thematic maps of the world (it was used as the primary world map projection by the National Geographic Society from 1988-1997, then replaced with another compromise projection, the Winkel Tripel; thus, the latter has become common in textbooks).

## What is a cylindrical projection equation?

Cylindric projection equations yield projected graticules with straight meridians and parallels that intersect at right angles. The example shown above is a Cylindrical Equidistant (also called Plate Carrée or geographic) in its normal equatorial aspect.

## What are latitude and longitude coordinates?

Latitude and longitude coordinates specify positions in a spherical grid called the graticule (that approximates the more-or-less spherical Earth). The true geographic coordinates called unprojected coordinate in contrast to plane coordinates, like the Universal Transverse Mercator (UTM) and State Plane Coordinates (SPC) systems, that denote positions in flattened grids. These georeferenced plane coordinates are referred to as projected. The mathematical equations used to project latitude and longitude coordinates to plane coordinates are called map projections. Inverse projection formulae transform plane coordinates to geographic. The simplest kind of projection, illustrated below, transforms the graticule into a rectangular grid in which all grid lines are straight, intersect at right angles, and are equally spaced. Projections that are more complex yield grids in which the lengths, shapes, and spacing of the grid lines vary. Even this simplest projection produces various kinds of distortions; thus, it is necessary to have multiple types of projections to avoid specific types of distortions. Imagine the kinds of distortion that would be needed if you sliced open a soccer ball and tried to force it to be completely flat and rectangular with no overlapping sections. That is the amount of distortion we have in the simple projection below (one of the more common in web maps of the world today).

## Why is a planar projection called azimuthal?

Planar projections are also called azimuthal because every planar projection preserves the property of azimuthality, directions (azimuths) from one or two points to all other points on the map. The projected graticule shown above is the result of an Azimuthal Equidistant projection in its normal polar aspect.

## What is a pseudodocylindric projection?

Pseudocylindric projections are variants on cylindrics in which meridians are curved. The result of a Sinusoidal projection is shown above. Conic projections yield straight meridians that converge toward a single point at the poles, parallels that form concentric arcs.

## What are the three types of flattenable surfaces to which the graticule can be projected?

Figure 2.15. Three types of “flattenable” surfaces to which the graticule can be projected: a plane, a cone, and a cylinder.

## How is the Robinson projection similar to the Equal Earth projection?

(2018) in their work as a starting point, is the most similar to Equal Earth projection in that this projection also does not distort in a significant way the appearance of the world. The main problem, however, is that to balance appearance and size, the Robinson projection gives away some accuracy in appearance and size to make it a compromising approach relative to projections that focus on appearance or area only. The meridians curve gently and distortions are limited, mostly along the poles. Nevertheless, inaccuracies in area mean that different regions are not representative to their true appearance. But, because the projection balances such inaccuracies to keep them at a minimum, it does serve as a starting point where one can try to fit area to be accurately shown while maintaining the shape of the projection so that continents and areas are not distorted in appearance. On the other hand, the Equal Earth projection, while appearing very similar to Robinson, improves on its weaknesses. Mainly, area is accurately shown while also keeping a pleasing way in which the projection is shown, that is it also minimizes distortion. Thus, it is arguably the first projection to accurately show area in a way that many can easily visually perceive and understand similar to the Robinson projection.

## What are the conditions for equal earth projection?

The Equal Earth projection uses four conditions that allow it to develop a way in which projection can be calculated. The first condition is there must be equal area. The second is that it is a pseudocylindrical projection, meaning that the parallels are unequally spaced. Meridians are equally spaced along the parallels. Finally, there is bilateral symmetry to maintain a x- and y-axis appearance similar to the Robinson projection. In effect, area is accurate while appearance is balanced to minimize distortions.

## Why is Robinson projection so bad?

The main problem, however, is that to balance appearance and size, the Robinson projection gives away some accuracy in appearance and size to make it a compromis ing approach relative to projections that focus on appearance or area only. The meridians curve gently and distortions are limited, mostly along the poles.

## What is the Gall-Peters projection?

Development of the Earth Earth Map Projection. Recently, Boston schools had announced the use of Gall-Peters projection as their new type of map projection for their maps. However, given the problem of Gall-Peters, researchers began to look for new ways tomake a projection sensible for area, navigation, and appearance.

## Why are maps in 2D so hard to understand?

The problem has traditionally been to accurately portray size of land masses and show them in a way that does not distort orientation or makes it hard to understand the map due to its odd appearance.

## Is the Equal Earth projection the same as Robinson?

On the other hand, the Equal Earth projection, while appearing very similar to Robinson, improves on its weak nesses. Mainly, area is accurately shown while also keeping a pleasing way in which the projection is shown, that is it also minimizes distortion.

## Is area accurate in Equal Earth?

In effect, area is accurate while appearance is balanced to minimize distortions. While some distortion is inevitable, these are very minimal in the Equal Earth projection. Overall, one can use area accurately and not feel the appearance is highly distorted.

## Why are map projections important?

Map projections are important in creating maps with map projections distorting the surface in some way. Some of the distortions on the maps are acceptable while other distortions are not acceptable depending on the purpose of the map. The map projection is classified depending on the type of projection surface on which the globe is projected …

## Which projection is an example of a cylindrical projection?

The north to south stretching equals east to west but grows with latitude faster than east to west stretching in the case of central cylindrical projection. Mercator projection is an example of cylindrical projection which became a standard map projection because of its ability to represent lines of steady course.

## What is cylindrical projection?

A cylindrical projection is any projection in which the meridians are mapped to parallel spaced vertical lines and latitudes are mapped to horizontal lines. The projections stretch from east to west according to their geometric constructions and are the same at any chosen latitude. Cylindrical projections are distinguished from each other by the north to south stretching denoted by φ. The north to south stretching equals east to west but grows with latitude faster than east to west stretching in the case of central cylindrical projection. Mercator projection is an example of cylindrical projection which became a standard map projection because of its ability to represent lines of steady course. Mercator distorts the size of geographical objects because its linear scale increases with the increase in latitude. The distortion caused by the Mercator distorts the perception of the entire planet by exaggerating the areas laying far from the equator.

## What is the scaling of a pseudocylindrical projection?

The scaling of the pseudocylindrical projections are straight along the central meridian and also along the parallels. On a pseudocylindrical map, points further from the equator have higher latitudes than other points, preserving the north-south relationship. Pseudocylindrical projections include sinusoidal with same horizontal and vertical scales.

## What is distortion in maps?

Map projections without distortions would represent the correct distance, direction, shapes, and areas on a map. However, map projections have distortions which depend largely on the size of the area being mapped. Scale distortions on maps are shown on the map by an ellipse of distortion or using scale factor which is the ratio of the scale at a given point to the true scale. Distortions on maps of countries or cities are not evident to the eye and can only be identified when computing distances and areas.

## Why is the Robinson projection not equal area?

The projection is neither equal-area nor conformal because of the compromise to show the whole planet. The meridians of the Robinson projection curves are gently stretching the poles into long lines.

## How does the mercator distort the size of geographical objects?

Mercator distorts the size of geographical objects because its linear scale increases with the increase in latitude. The distortion caused by the Mercator distorts the perception of the entire planet by exaggerating the areas laying far from the equator.

## What is equivalent projection?

Equivalent projections preserve areal relationships. This means that comparisons between sizes of land-masses (e.g., North America vs. Australia) can be properly made on equal area maps. Unfortunately, when areal relationships are maintained, shapes of landmasses will inevitably be distorted—it is impossible to maintain both.

## What are the projections on maps?

These include equivalent projections (which preserve areal relationships), conformal projections (angular relationships), azimuthal projections (directional relationships), and equidistant projections (distance relationships). The projection you choose will depend on the characteristics most important to be preserved, given the purpose of your map.

## What is a Gnomonic Map Projection?

The gnomonic map projection has the interesting property that any straight line drawn on the projection is a great circle route. The gnomonic projection is an example of an azimuthal projection.

## Why are equidistant projections useful?

Equidistant projections are often useful as they maintain distance relationships. However, they do not maintain distance at all points across the map. Instead, an equidistant projection displays the true distance from one or two points on the map (dependent on the projection) to any other point on the map or along specific lines.

## How do conformal projections preserve local angles?

Though the scale factor (map scale) changes across the map, from any point on the map, the scale factor changes at the same rate in all directions , therefore maintaining angular relationships. If a surveyor were to determine an angle between two locations on Earth’s surface, it would match the angle shown between those same two locations on a conformal projection.

## What does it mean when landmasses are stretched East-West?

When these convergence points are instead mapped as lines, landmasses are stretched East-West, which means that to maintain the same area, landmasses must be compressed in the opposite direction.

## What is the shortest path between two points on Earth?

The shortest point between two points on Earth is called a great circle route. Unlike rhumb lines, such lines appear curved on a conformal projection (Figure 5.5.4). Of course, the literal shortest path from Providence to Rome is actually a straight line: but you’d have to travel beneath Earth’s surface to travel it.

## What is equal area map?

In map projection, equal-area maps preserve area measure, generally distorting shapes in order to do that. Equal-area maps are also called equivalent or authalic . Several equivalent projections were developed in an attempt to minimize the distortion of countries and continents of planet Earth, keeping the area constant.

## What does equal area representation mean?

Equal area representation implies that a region of interest in a particular portion of the map will share the same proportion of area as in any other part of the map.

## Projection Properties

• We often talk about map projections in terms of the ways in which they distort or preserve certain things about the Earth, which we call projection properties. There are four main properties:

## Choosing A Projection

• Since there are so very many projections, the question becomes: which one should you use? As you may imagine, the fact that there are so many means there is no “best” projection. Each has advantages and disadvantages and is better suited to certain situations. Here are some questions to ask yourself when choosing a projection: Is there any specific property that you need to prese…

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## Projection Parameters

• Once you know what projection you’re going to be using, there’s one final step. As we discussed above, each projection has places where distortion is worse, and places where it is not too bad. Fortunately, we get to pick the place where distortions are minimal when we’re setting up a projection. This means we can always make sure that the subject of our map is the part that ha…

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## Our Recommendations

• There is never a single “right answer” when choosing a map projections; the best choices depend on weighing all the factors described above. However, there are few facts and rules of thumb that can help narrow your choices. If you’re working with web maps, you will often have no choice but Mercator. Be aware that this projection is widely considered inappropriate for many kinds of the…

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## Overview

In cartography, map projection is the term used to describe a broad set of transformations employed to represent the two-dimensional curved surface of a globe on a plane. In a map projection, coordinates, often expressed as latitude and longitude, of locations from the surface of the globe are transformed to coordinates on a plane. Projection is a necessary step in creating a two-dimen…

## Design and construction

The creation of a map projection involves two steps:
1. Selection of a model for the shape of the Earth or planetary body (usually choosing between a sphere or ellipsoid). Because the Earth’s actual shape is irregular, information is lost in this step.
2. Transformation of geographic coordinates (longitude and latitude) to Cartesian (x,y) or polar (r, θ) plane coordin…

## Metric properties of maps

Many properties can be measured on the Earth’s surface independently of its geography:
• Area
• Shape
• Direction

## Classification

A fundamental projection classification is based on the type of projection surface onto which the globe is conceptually projected. The projections are described in terms of placing a gigantic surface in contact with the Earth, followed by an implied scaling operation. These surfaces are cylindrical (e.g., Mercator), conic (e.g., Albers), and plane (e.g., stereographic). Many mathematical projections, however, do not neatly fit into any of these three conceptual projection methods. He…

## Projections by surface

The three developable surfaces (plane, cylinder, cone) provide useful models for understanding, describing, and developing map projections. However, these models are limited in two fundamental ways. For one thing, most world projections in use do not fall into any of those categories. For another thing, even most projections that do fall into those categories are not naturally attain…

## Projections by preservation of a metric property

Conformal, or orthomorphic, map projections preserve angles locally, implying that they map infinitesimal circles of constant size anywhere on the Earth to infinitesimal circles of varying sizes on the map. In contrast, mappings that are not conformal distort most such small circles into ellipses of distortion. An important consequence of conformality is that relative angles at each point of …

## Which projection is best?

The mathematics of projection do not permit any particular map projection to be best for everything. Something will always be distorted. Thus, many projections exist to serve the many uses of maps and their vast range of scales.
Modern national mapping systems typically employ a transverse Mercator or close variant for large-scale maps in order to preserve conformality and low variation in scale over small areas. For small…

• Geodetic datum
• Geographic information system (GIS)
• Geoinformatics
• Grid reference
• List of map projections

## Offsetting Distortion of Land Masses

The Mercator projection, first appearing in 1569, which had been popular and is still commonly seen in classrooms, has been heavily criticized for its distortion of land masses and their areas, particularly near the poles (e.g,. Greenland appearing far larger than it actually is). One popular response was the Gall-Peters projection, wh…

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## Other Equal Area Map Projections

• The Gall-Peters projection is not the only equal area projection. The Sinusoidal projection, for instance, provides an equal area projection. However, like the Gall-Peters projection, the appearance is heavily distorted to make way for accurate area, which makes it distorting for the viewer to look at since the expectation of a cylindrical form is …

## Development of The Earth Earth Map Projection

• Recently, Boston schools had announced the use of Gall-Peters projection as their new type of map projection for their maps. However, given the problem of Gall-Peters, researchers began to look for new ways tomake a projection sensible for area, navigation, and appearance. This led to the development of the Equal Earth map projection, which has quickly gained influence due to it…

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## References

• For more on the problematic nature of popular projections previously used, see: Pearson, F. (1990). Map projections: theory and applications. Boca Raton, Fla: CRC Press. For more on the Sinusoidal projection and comparison to other projections, see: Tobler, W. R. (1986). Measuring the Similarity of Map Projections. The American Cartographer, 13(2), 135–139. https://doi.org/1…

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